U.S. patent application number 11/961946 was filed with the patent office on 2010-10-21 for system and method to centrifugally cast munitions.
Invention is credited to Steven W. Mitchell.
Application Number | 20100263522 11/961946 |
Document ID | / |
Family ID | 42979994 |
Filed Date | 2010-10-21 |
United States Patent
Application |
20100263522 |
Kind Code |
A1 |
Mitchell; Steven W. |
October 21, 2010 |
SYSTEM AND METHOD TO CENTRIFUGALLY CAST MUNITIONS
Abstract
An apparatus for manufacturing munitions includes a housing and
a munition mold within the housing. The housing has an axis of
rotation. The munition mold is filled with a molten metal, and the
mold is rotated to form a munition.
Inventors: |
Mitchell; Steven W.;
(Manassas, VA) |
Correspondence
Address: |
SCHWEGMAN, LUNDBERG & WOESSNER, P.A.
P.O. BOX 2938
MINNEAPOLIS
MN
55402
US
|
Family ID: |
42979994 |
Appl. No.: |
11/961946 |
Filed: |
December 20, 2007 |
Current U.S.
Class: |
86/51 |
Current CPC
Class: |
B22D 13/04 20130101;
F42B 33/00 20130101 |
Class at
Publication: |
86/51 |
International
Class: |
B21K 21/06 20060101
B21K021/06 |
Claims
1. A process comprising: forming a molten metal by melting a matrix
metal; adding a reinforcing metal fiber to the molten metal;
filling a munition mold with the molten metal; and rotating the
mold to form a single-piece munition; wherein the reinforcing metal
fiber comprises materials of two or more different densities such
that the rotating forms a density gradient along the length of the
munition.
2. (canceled)
3. (canceled)
4. The process of claim 1, wherein the reinforcing metal fiber
comprises one or more of a reinforcing whisker, a metal wire, a
metal rod, and a sheet metal.
5. (canceled)
6. (canceled)
7. The process of claim 4, wherein the density gradient originates
at a butt end of the munition and increases in density to a tip end
of the munition.
8. The process of claim 1, comprising altering the density of the
molten metal matrix to affect the density gradient of the
munition.
9. The process of claim 1, wherein the munition mold comprises a
radius, a circumference, and a plurality of individual molds
substantially aligned along radii.
10. The process of claim 1, comprising altering the rotational
velocity of the mold to affect the density gradient of the
munition.
11. The process of claim 1, further comprising the munition.
12-20. (canceled)
Description
TECHNICAL FIELD
[0001] Various embodiments relate to the manufacture of munitions,
and in an embodiment, but not by way of limitation, to
centrifugally cast munitions.
BACKGROUND
[0002] Current anti-submarine warfare and anti-mine munitions
(e.g., darts, projectiles, torpedoes, and other high performance
penetrating projectiles) are manufactured by machining multiple
pieces of various materials (such as tungsten, aluminum, and
steel), and then assembling those pieces to obtain the requisite
material properties such as center of mass, hardness, and shape.
This requires multiple machining and assembly steps, all of which
require skilled labor resulting in increased unit costs. Moreover,
joints between the component parts are potential points of
weakness, and darts constructed in this way have been observed
during testing to break apart while penetrating the water-air or
the air-ground interfaces due to unsustainable torque across a
joint.
BRIEF DESCRIPTION OF THE DRAWINGS
[0003] FIG. 1 is a top view of an example embodiment of an
apparatus to centrifugally cast munitions.
[0004] FIG. 2 is a side view of an example embodiment of an
apparatus to centrifugally cast munitions.
[0005] FIG. 3 illustrates an example embodiment of a process to
centrifugally cast munitions.
[0006] FIG. 4 illustrates another example embodiment of a process
to centrifugally cast munitions.
DETAILED DESCRIPTION
[0007] In the following detailed description, reference is made to
the accompanying drawings that show, by way of illustration,
specific embodiments in which the invention may be practiced. These
embodiments are described in sufficient detail to enable those
skilled in the art to practice the invention. It is to be
understood that the various embodiments of the invention, although
different, are not necessarily mutually exclusive. Furthermore, a
particular feature, structure, or characteristic described herein
in connection with one embodiment may be implemented within other
embodiments without departing from the scope of the invention. In
addition, it is to be understood that the location or arrangement
of individual elements within each disclosed embodiment may be
modified without departing from the scope of the invention. The
following detailed description is, therefore, not to be taken in a
limiting sense, and the scope of the present invention is defined
only by the appended claims, appropriately interpreted, along with
the full range of equivalents to which the claims are entitled. In
the drawings, like numerals refer to the same or similar
functionality throughout the several views.
[0008] One or more figures show block diagrams of systems and
apparatus of embodiments of the invention. One or more figures show
flow diagrams illustrating systems and apparatus for such
embodiments. The operations of the flow diagrams will be described
with references to the systems/apparatuses shown in the block
diagrams. However, it should be understood that the operations of
the flow diagrams could be performed by embodiments of systems and
apparatus other than those discussed with reference to the block
diagrams, and embodiments discussed with reference to the
systems/apparatus could perform operations different than those
discussed with reference to the flow diagrams.
[0009] In the art of munitions, proper performance requires tight
control of external shape, mechanical properties, and mass
properties. Careful engineering with thorough modeling, analysis,
and testing can produce darts made of multiple pieces that do not
break apart in flight. However, the current manufacturing approach
is inherently costly. The combined requirements of tight control of
mass properties, physical properties (including shape and
strength), and low production costs in the past have been addressed
only by outsourcing production to low labor cost areas. However,
even if labor costs can be virtually eliminated, darts made of
multiple components are likely to be significantly more expensive
than cast darts.
[0010] In an embodiment, near-net-shaped darts are cast in a
centrifugal casting machine from a metal matrix composite such as
tungsten fibers in an aluminium alloy matrix. The long axis of the
mold for the dart is normal to the axis of rotation, with the point
of the dart farthest away from the axis. Multiple darts may be cast
at once, with the individual dart molds arranged like spokes
radiating from the axis of rotation. This arrangement can be
referred to as a "wagon wheel." The metal matrix composite can be
poured through a tundish that is coupled to the axis of rotation.
The casting machine is spun at an appropriate speed to get the
desired segregation of heavy components away from the axis of
rotation. As the metal matrix composite cools in the dart molds,
the heavy composite fibers (e.g., tungsten) concentrate in the nose
of the dart, thereby providing the required mass distribution. The
cooling rate is controlled to produce the required continuous
distribution of heavy composite fibers down the length of the dart,
thereby providing the desired mechanical properties such as
strength. Metal or shell molds can be used in this process,
producing castings which require little or no machining to meet the
dimensional requirements.
[0011] FIGS. 1 and 2 illustrate an example embodiment of an
apparatus 100 for centrifugally casting munitions. The apparatus
100 includes a housing 110, a munition mold 130 within the housing
110, and an axis of rotation 120. In the embodiment of FIG. 1, the
housing 110 is circular, thereby forming a radius and a
circumference. As illustrated in FIG. 1, the housing 110 can
include a plurality of munition molds 130 that are substantially
aligned along the radius of the housing 110, thereby forming a
"wagon wheel" of molds 130. The munition molds 130 can include an
anti-submarine munition mold, an anti-mine munition mold, and/or
molds for other munitions now known in the art or later developed.
The apparatus 100 can further include a means to rotate the housing
and mold about the axis of rotation. An example of such a means is
an electric motor or combustion engine, coupled to some sort of
drive train and/or gear system to create the rotation. The
apparatus can further include a means to alter the rotation speed
of the housing, such as a variable speed motor. The apparatus 100
can further include a tundish 140. The tundish 140 is for receiving
a molten metal that is used to form the munitions in the mold 130.
In another example embodiment, the molds 130 can be stacked upon
one another (that is, two or more wagon wheels are stacked upon
each other). In such a stacked embodiment, the tundish 140 is
coupled to each stack level.
[0012] FIG. 3 is a flowchart of an example process 300 for
centrifugally casting munitions. FIG. 3 includes a number of
process blocks 310-355. Though arranged serially in the example of
FIG. 3, other examples may reorder the blocks, omit one or more
blocks, and/or execute two or more blocks in parallel.
[0013] In the process 300, starting at 310, a munition mold is
filled with a molten metal. As noted above, the munition can be an
anti-submarine munition, an anti-mine munition, and/or some other
type of munition now known or later developed. At 315, the mold is
rotated to form a munition. At 320, the molten metal is formed by
melting a powdered matrix metal. At 323, reinforcing metal fibers
are added to the molten metal matrix. Examples of reinforcing metal
fiber includes reinforcing whiskers (typically single crystals of
metal), metal rods, metal wires, and sheet metal strips. At 325,
the rotation of the mold generates a density gradient along the
length of the munition. At 330, the density gradient originates at
the butt end of the munition and increases in density along the
munition to the tip end of the munition. At 335, the density of the
molten metal matrix is altered to affect the density gradient of
the munition. This density can be affected with a mix of high
melting point metals and low melting point metals. At 345, a
plurality of reinforcing metal fibers of two or more different
densities are provided so as to affect the density gradient of the
munition. At 350, the munition mold includes a radius, a
circumference, and a plurality of individual molds that are
substantially aligned along the radius of the mold. At 355, the
rotational speed of the mold is altered to affect the density
gradient of the munition.
[0014] FIG. 4 is a flowchart of another example embodiment of a
process 400 for centrifugally casting munitions. At 405, the
munition molds are manufactured. At 410, the molds are assembled
into a centrifugal casting machine. At 415, the casting machine is
spin up. The mold may be pre-heated, and if pre-heated, it may be
done either before spinning up or while spinning up. Pre-heating a
mold helps avoid thermal stress shattering which could result from
pouring the molten metal matrix into a cold mold. Pre-heating a
mold also aids in uniform filling of the mold. At 420, a powdered
metal matrix is provided, and at 425, that metal matrix is melted.
At 430, one or more reinforcing metal fibers are provided, and at
435, the melted metal matrix and the reinforcing metal fibers are
blended into a composite. If there are multiple species of
reinforcing metal fibers, they may be added all at once or
sequentially. At 440, the molten metal matrix is poured into the
molds via a tundish, and at 445, the munitions are cast. If the
molds are in a multi-level stack, the amount of molten metal matrix
can be varied to fill the desired number of molds. After spinning
for the desired period of time, the casting machine is spun down at
450. The molds are then opened at 455, and the munitions removed at
460.
[0015] Thus, an example system and method for centrifugally casting
munitions has been described. Although specific example embodiments
have been described, it will be evident that various modifications
and changes may be made to these embodiments without departing from
the broader scope of the invention. Accordingly, the specification
and drawings are to be regarded in an illustrative rather than a
restrictive sense. The accompanying drawings that form a part
hereof, show by way of illustration, and not of limitation,
specific embodiments in which the subject matter may be practiced.
The embodiments illustrated are described in sufficient detail to
enable those skilled in the art to practice the teachings disclosed
herein. Other embodiments may be utilized and derived therefrom,
such that structural and logical substitutions and changes may be
made without departing from the scope of this disclosure. This
Detailed Description, therefore, is not to be taken in a limiting
sense, and the scope of various embodiments is defined only by the
appended claims, along with the full range of equivalents to which
such claims are entitled.
[0016] Such embodiments of the inventive subject matter may be
referred to herein, individually and/or collectively, by the term
"invention" merely for convenience and without intending to
voluntarily limit the scope of this application to any single
invention or inventive concept if more than one is in fact
disclosed. Thus, although specific embodiments have been
illustrated and described herein, it should be appreciated that any
arrangement calculated to achieve the same purpose may be
substituted for the specific embodiments shown. This disclosure is
intended to cover any and all adaptations or variations of various
embodiments. Combinations of the above embodiments, and other
embodiments not specifically described herein, will be apparent to
those of skill in the art upon reviewing the above description.
[0017] The Abstract is provided to comply with 37 C.F.R.
.sctn.1.72(b) and will allow the reader to quickly ascertain the
nature and gist of the technical disclosure. It is submitted with
the understanding that it will not be used to interpret or limit
the scope or meaning of the claims.
[0018] In the foregoing description of the embodiments, various
features are grouped together in a single embodiment for the
purpose of streamlining the disclosure. This method of disclosure
is not to be interpreted as reflecting that the claimed embodiments
have more features than are expressly recited in each claim.
Rather, as the following claims reflect, inventive subject matter
lies in less than all features of a single disclosed embodiment.
Thus the following claims are hereby incorporated into the Detailed
Description, with each claim standing on its own as a separate
example embodiment.
* * * * *